Thermostatic time-element device.



N. WILKINSON. THEEMOSTATIG TIME ELEMENT DEVICE.

APPLIOATION FILED JULY 28, 1911.

1,030,555. Patented June 25,1912.

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BMW/11 @(ovWwm QWMWM UNITED STATES ATENT orFmE.

murmur wm mon, or. nILwAnKnn, Wisconsin," Assrcmon To mms cnALmEns coups-1w, "A CORPGBATION or new Jens-E1 ori inal application filed 11 1:1117, 1911, Serial jNo. 621,665. 1 Divided and thi's-applicationflled July 28, 1911. seri 11te.e41,157. L I 1 To all whom it may concern:

Be it'known that I, NATHAN. WILKINSON,

a citizen of the United Statea residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in :Thermostatic Time-Element Devices, of which the following is a clear, and exact specif'r cation.

invention' relates to 'therm ostatic timee'lement devices. 7 p This application is a division of my copending application Serial No. 62 1,665,filed It is the obj ect of my present invention to provide a thermostatic time element device which is reliable and accurate; and athermostatic switchwhichoperates with asnap action, thus avoiding arcing at the switc contacts, and is automatically reset. The various novel features of my invention will be apparent from the description pointed out incthe claims.

and drawings, and will be particularly 'Figure 1 shows a system embodyihg my 'invention, the switch actuated by the thermostat b'eing'inolosed position; and Fig. '2

shows the 'sameithermostatic switch 'just after it has been trippedg The thermostat proper is preferably of the form described and claimed in my afore- ,said' co-pending application, of which this is aadivisiom' It consists of two metal strips or rods 10 and ll. The strip. 10 is preferably" made of'a brass tube with the ends flattened, whilethe strip '11 is made of a flat steel spring. However, the strips-may be made of any desired-material, and are; not

necessarily ofunlike material. .The' 'left' hand ends ofthe strips 10 andll are mount- -'ed i i-common on a post 12, being. spaced "apart by a thick washer 13 and held in placev by a screw 14f.- Their right hand ends are" fastened together in any desired man- 'ner, as by rivets or solder, or by a screw 15,

the latter also serving as an adjusting screw which may be locked in position by a hook 16 forme'dbyan extension of the spring strip 11. .The'strip or tube-10 is wound with aheatingj-coilfl, one end of wh1c'h is con- 7 the bottom of-la contactterminal 23, the two contact terminals 18 and23- being normally L k 21, and'cooperates with a fixed-contact 22 at e es-mama 0'! resume, PatentedJune 25,1912.

bridged by a member 24 which may. be lifted out of engagement with one or; both by an overload coil. 25.v The bridging member 2 1 thus short-circuits the heating-coil. 17 and the switch 19. Pivotedto the lower endof the vertical arm ofthebell-crank lever 21 is V a se'cond'bell-crank lever '26, thelong horizontal arm of which extends above and substantially parallel to the strip 11 and may be engaged near its fulcrum by' the adjustingscrew 15. The bell-crank levers 21 and 26 are biased in clockwise and counter-clockwise directions respectively bya spring 27,

but are normally held from movement in such directions bythe weight of; the bridging member 24 resting onthe screw'28 carried by the-horizontal 'armof the bell-crank lever. 21, and by astop 29 withwhich a notch at the endof, the horizontal arm of the bell-crank lever 26 engages.

The thermostat and' switch above described are shown as controlling a circuitbreaker 30, arrangedin the mains 31-of an electrical distribution-s stem of any desired type. The circuit-breaker is biased to open voltage coil 32, the circuit of which includes the contact terminals 18 and 23 and some connection between them. Thisconnectionis normallyjthe bridging, member 2 1, the parts being as shown in Fig. 1. Upon an 'position, but may be heldclosed by the nO- voltage coil 32to-pass through-the heating coil 17 and the-switch 19 and 22. The coil-'17 immediately to heat the strip or; tube '10, causing ittoexpand longltudinally and raise the ri ht hand or joined.

ends of the-strips 10 an 11. The coil. 17 has little orqno heating effect on the strip 11.

If tlidoverloadis but momentary,- the overload coil 25 allows the bridging member 24:

to drop to short-circuit the heating coil 17 and the s witchcontacts 19' and.22.. If the overloadicontinues, however, the expansion of the tube 10 under the influence of the' heatingcoilfl continues the screw 15 has liftedtthe left hand end of'the horlzontal arm of the bell-crank lever 26 clear 'of, the stop 29, whereupon the spring 27 immeand- 19 to the left,' to the position shown in Fig. 2. This separates the switch contacts 1.9 and 22, thus breaking the circuit of the no-voltage coil 32 and tripping the circuitbreaker 30. Upon the opening of the cirunit-breaker 30 and the consequent deenergization of the overload magnet 25, the bridging member 24: drops and forces the screw 28 downward, thus moving the contact 19 again into engagement with the contact 22, and the bell-crank lever 26 at least far enough to theright to allow the notch at its end to engage the stop '29.- Since it takes some little time for the strip 10 to cool and contract to its former length, such notch does not immediately engage the stop 29. Thus if the circuit breaker 30 is immediately re-closed it will immediately be retripped if the overload still continues, for the lifting of the bridging member 24% by the magnet allows the immediate separation of the contacts 19 and 22 and the immediate interruption of the circuit of the no-voltage' magnet 32. However, if the circuit-breaker is not immediately re-closed, or if it is re closed but the overload has ceased, the bridging member 24 will remain down, and hold the .contacts 19' and 22 in engagement until by the cooling and contraction of the crank lever 26 has 'againengaged the stop 29. If an overload then occurs, the circuit-- breaker 30 will be tripped only after an interval of time, in the manner above described. This interval of time maybe adjusted with great accuracy by the screw 15.

The thermostatic time element device above described is capable of wide modification from the specific arrangement shown,

, and I aimin my claims to cover every such modification which does not involve a debiased to one position, a latch for-holdingsaid switch in the other position, a thermojstat for tripping said latch, and automatic parture from the spirit andscope of my invention as defined the following claims. What I claim as new is; V 1. In combination, a switch normally means for resetting the switchi'n the latched position. e

2. In combination, a switch biased to open position, a latch for holding said switch in closed position, a thermostat for tripping said latch, a heating coil for said therm o'- stat, said coil being in series with $3.16.

switch, a second switch which when closed short-circuits said heating coil, and means for opening said second switchupon the occurrence of predetermined abnormal condi-' tions.

3. Incombination, a switch biased to-aepen position, a latch for holding said switch in closed position, .a thermostat for tripping said latch, a'heating coil for sald thermostat, said coil being in series with said switch, a second switch which when closed.

short-circuits said heating coil, means for opening said second switchupon the occurrence of predetermined abnormal condi tions, and means operated by the closing of said second switch for reset-ting the first switch in closed position.

4. in combination, a switch biased to open position, a latch for holding said switch in closed position, a thermostat which when heated trips said latch, a heating coil for said thermostat, said heating coil being connected in series with said switch, and a secswitch which when closed short-circuits said heating coil, a circuit-breaker, a no-voltage tripping magnet therefor, the circuit of said tripping magnet being broken when said two switches are open at the same time, and means for opening the second switch upon the occurrence of abnormal conditions in the circuit supplied through said circuitbreaker.

6. In position, a latch for holding said switch in another position, a thermostat fdr tripping said latch, andautomatic means for resetting the switch in the latched position.

combination, a switch'biased to open loo 7. In combination, a switch normally closed and biased to open position, a latch for holding said switch'in closed position, primary means comprising a thermostat for tripping said latch, and automatic means for resetting the switch in the latched position. r 8. In combination, a switch normally biased to one position, means for holding said switch in the other position, a-thermostat when actuated by increase of heat rendering said means ineifective, and automatic means for resetting the switch in the position held by said first mentioned means. 9. In combination, a switch biased to open position, a latch for holding said switch in closed po'sition,'a thermostat which when heated trips said latch, and a heating coil forsaid thermostat, said heating coil being connected in series with said switch, and automatic means for resetting the switch in a latched position. v

1C. In combination, a switch biased to open position,- means for holding said switch in closed position, a thermostat which when 7 connected in series-with said'switch, and a second switchwhich when closed short-cir- 11,030,555, I i 's cuits said heating coil, said second switch being adapted to close automatically.

11. In combination, a switch normally biased to one positionymeans for holding said switch in another position, a thermostat which when heated being adapted to render said means ineffective, a heating coil for said thermostat, said heating coil being connected in series with said switch, a sec-'' when said two switches are openat the same time, and means for opening the second 15 switch upon'the occurrence of abnormal conditions in the circuit supplied through said circuit-breaker. v 7 Milwaukee, Wis, July 20, 1911.

In testimony whereof I afiix my signature, 20 in the presence of two witnesses.

NATHAN WILKINSON.

-ROB. E. STOLL. Y 

